Hi Mal,Mal wrote:Hi Stephen, and welcome.
I read that once you get to the higher tensile bolts, spring washers are no longer functional as they cannot make any indent to the head of the bolt.
At what grade of bolt are spring washers not necessary? What type of washer, if any should you use?, or should you just make sure that they are torqued to the correct spec?.
Thanks Mal
What you are describing sounds more like a shakeproof washer. Spring washers do not make an indent into the head of the bolt; they compress and the resulting tension prevents the fastener from vibrating loose. There has been some debate about how effective they are at doing this, but in general I'd say they are suitable for usage with higher grade bolts such as SAE grade 8.
The teeth on shakeproof washers make an indent into the head of the bolt, so these washers are not suitable for usage with higher grade fasteners as the hardness prevents an indent being made, as you said.
Regarding flat washers, it is advisable to use hardened washers on SAE Grade 8 (equivalent grades are ISO 10.9 in Metric, Grade V in imperial) and above.
Hope this helps.
Best Regards,
Stephen